Abstract
Soil physicochemical properties, soil microbial biomass and bacterial community structures in a rice-wheat cropping system subjected to different fertilizer regimes were investigated in two seasons (June and October). All fertilizer regimes increased the soil microbial biomass carbon and nitrogen. Both fertilizer regime and time had a significant effect on soil physicochemical properties and bacterial community structure. The combined application of inorganic fertilizer and manure organic-inorganic fertilizer significantly enhanced the bacterial diversity in both seasons. The bacterial communities across all samples were dominated by Proteobacteria, Acidobacteria and Chloroflexi at the phylum level. Permutational multivariate analysis confirmed that both fertilizer treatment and season were significant factors in the variation of the composition of the bacterial community. Hierarchical cluster analysis based on Bray-Curtis distances further revealed that bacterial communities were separated primarily by season. The effect of fertilizer treatment is significant (P = 0.005) and accounts for 7.43% of the total variation in bacterial community. Soil nutrients (e.g., available K, total N, total P and organic matter) rather than pH showed significant correlation with the majority of abundant taxa. In conclusion, both fertilizer treatment and seasonal changes affect soil properties, microbial biomass and bacterial community structure. The application of NPK plus manure organic-inorganic fertilizer may be a sound fertilizer practice for sustainable food production.
Highlights
Soils are considered to be the most diverse microbial habitats on Earth with respect to species diversity, community size and microbial biomass [1,2]
The soil organic matter (OM) content was higher in October (29.3 g/kg) than in June (24.0 g/kg), while the soil total P (TP) content was higher in June (1.09 g/kg) than in October (0.68 g/kg)
The results demonstrate that both fertilizer treatment and season were found to impact soil chemical parameters, microbial biomass, bacterial abundance and bacterial community structure
Summary
Soils are considered to be the most diverse microbial habitats on Earth with respect to species diversity, community size and microbial biomass [1,2]. Bacteria are the most abundant and diverse group of soil microorganisms [3], playing a vital role in agroecosystems through participation in recycling soil nutrients, maintaining soil structure and promoting plant growth [4,5]. It has long been recognized that the appropriate community structure, abundant diversity and a high activity of microorganisms are significant factors in maintaining the sustainability and productivity of ecosystems [6,7,8,9]. Fertilization is an important agricultural practice for improving plant nutrition, increasing soil organic matter and achieving high crop yields, but it can affect soil microbial abundance, activity and community structure [10,11,12,13]. Significant differences in soil microbial biomass and microbial diversity have been observed following fertilization [14,15,16]. Organic fertilizers usually increase soil microbial biomass [17,18], enzyme activities [13,19] and functional diversity [16], while microbial biomass and enzyme activities are decreased in response to inorganic fertilizers [20,21,22]
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